1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
2 | /* |
3 | * CTR: Counter mode |
4 | * |
5 | * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au> |
6 | */ |
7 | |
8 | #ifndef _CRYPTO_CTR_H |
9 | #define _CRYPTO_CTR_H |
10 | |
11 | #include <crypto/algapi.h> |
12 | #include <crypto/internal/skcipher.h> |
13 | #include <linux/string.h> |
14 | #include <linux/types.h> |
15 | |
16 | #define CTR_RFC3686_NONCE_SIZE 4 |
17 | #define CTR_RFC3686_IV_SIZE 8 |
18 | #define CTR_RFC3686_BLOCK_SIZE 16 |
19 | |
20 | static inline int crypto_ctr_encrypt_walk(struct skcipher_request *req, |
21 | void (*fn)(struct crypto_skcipher *, |
22 | const u8 *, u8 *)) |
23 | { |
24 | struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); |
25 | int blocksize = crypto_skcipher_chunksize(tfm); |
26 | u8 buf[MAX_CIPHER_BLOCKSIZE]; |
27 | struct skcipher_walk walk; |
28 | int err; |
29 | |
30 | /* avoid integer division due to variable blocksize parameter */ |
31 | if (WARN_ON_ONCE(!is_power_of_2(blocksize))) |
32 | return -EINVAL; |
33 | |
34 | err = skcipher_walk_virt(walk: &walk, req, atomic: false); |
35 | |
36 | while (walk.nbytes > 0) { |
37 | u8 *dst = walk.dst.virt.addr; |
38 | u8 *src = walk.src.virt.addr; |
39 | int nbytes = walk.nbytes; |
40 | int tail = 0; |
41 | |
42 | if (nbytes < walk.total) { |
43 | tail = walk.nbytes & (blocksize - 1); |
44 | nbytes -= tail; |
45 | } |
46 | |
47 | do { |
48 | int bsize = min(nbytes, blocksize); |
49 | |
50 | fn(tfm, walk.iv, buf); |
51 | |
52 | crypto_xor_cpy(dst, src1: src, src2: buf, size: bsize); |
53 | crypto_inc(a: walk.iv, size: blocksize); |
54 | |
55 | dst += bsize; |
56 | src += bsize; |
57 | nbytes -= bsize; |
58 | } while (nbytes > 0); |
59 | |
60 | err = skcipher_walk_done(walk: &walk, err: tail); |
61 | } |
62 | return err; |
63 | } |
64 | |
65 | #endif /* _CRYPTO_CTR_H */ |
66 | |